Replay Media Player freezes Firefox

I'm running Vista, the latest updates are all installed.
I'm running AVG 8.5.285 as my only anti-virus software.

My problem is this - yesterday I downloaded AVG for the first time. I hadn't been running any anti-virus software on this computer before that (I know, stupid), so the first thing I did was run a scan. AVG found nothing.

Then today, AVG tells me that it's found a problem file, petolahu.dll. I clean one file, then delete the others that suddenly show up, because according to AVG they can't be found.

After this, Firefox doesn't load at all, just gives me a white screen. So I assume I shouldn't have deleted the files, and restore what I can from AVG's virus vault. Now, Firefox works, but when I run Replay Media Catcher (a program I've never had a problem with before), Firefox freezes completely.

Obviously I'm trying to find information on AVG as well at different sites than this one, to see if it's a problem with the program since that's where the problem started. Before then, everything ran fine (although I was getting pop-ups every once in a while since yesterday morning, before the AVG download).

If there's any other information necessary before anyone can offer any solutions, please just let me know.

I'd really appreciate any help anyone can give me.